Background The YIGSR is a pentapeptide, from the laminin-1 of the β1 chain, which can mediate cell adhesion and bind the 67 kD laminin receptor. The purpose is to evaluate the usefulness of 99m Tc-YIGSR, a novel tumour radiotracer, in the receptor imaging of Ehrlich ascites tumour. Methods Using S-Acetly-NH_3-MAG_3 as chelate, YIGSR, a pentapeptide from laminin, was tagged with 99m Tc. 99m Tc-YIGSR was detected in the tumour group bearing Ehrlich ascites tumour and blocked group. Tumour, normal, inflammatory and blocked groups were imaged. Results Through reverse phase Sep-Pak C_ 18 chromatogram, it was revealed that YIGSR could conjugate with S-Acetly -NH_3-MAG_3, and be radiolabelled at room temperature and neutral pH with a radiolabelling yield of 62%, and of 4% without chelate. 99m Tc-YIGSR was rapidly cleared from kidney, then liver. The imaging findings showed tumour tissue accumulated initial radioactivity at fifteen minutes after injection in the tumour group, and the uptake increased to peak at three hours with a tumour/muscle ratio (T/M) of 11.36, then cleared slowly to a T/M of 7.50 at eight hours. The tumour uptake of radiotracer in blocked group was significantly lower with T/M of 4.61 at three hours and 0.89 at eight hours. The T/M was only 3.72 at three hours and 1.29 at eight hours after injection in inflammatory group. Compared with inflammatory group and control obstructive group, the ratio of T/M in tumour group was significantly different ( P <0.001). Conclusions Using S-Acetly-NH_3-MAG_3, we radiolabelled YIGSR with 99m Tc. 99m Tc-YIGSR possesses many merits of tumour imaging: rapid visualization, high sensitivity and specificity, and satisfactory target/nontarget ratio. Our data suggest 99m Tc-YIGSR is a promising tumour radiotracer. Background The YIGSR is a pentapeptide, from the laminin-1 of the β1 chain, which can mediate cell adhesion and bind the 67 kD laminin receptor. The purpose is to evaluate the usefulness of 99m Tc-YIGSR, a novel tumor radiotracer, in the receptor imaging of Ehrlich ascites tumor. Methods Using S-Acetly-NH3-MAG_3 as chelate, YIGSR, a pentapeptide from laminin, was tagged with 99m Tc. 99m Tc-YIGSR was detected in the tumor group bearing Ehrlich ascites tumor and blocked group. Tumour, normal, inflammatory and blocked groups were imaged. Results Through reverse phase Sep-Pak C_ 18 chromatogram, it was revealed that YIGSR could conjugate with S-Acetly -NH_3-MAG_3, and be radiolabelled at room temperature and neutral pH with a radio label Yield of 62%, and of 4% without chelate. 99m Tc-YIGSR was rapidly cleared from kidney, then liver. The imaging findings showed tumor tissue initialized radioactivity at fifteen minutes after injection in the tumor The uptake of radiotracer in blocked group was significantly lower with T / M of 4.61 at three hours and 0.89 at eight hours. The T / M was only 3.72 at three hours and 1.29 at eight hours after injection in inflammatory group. Compared with inflammatory group and control obstructive group, the ratio of T / Conclusions Using S-Acetly-NH3-MAG_3, we radiolabelled YIGSR with 99m Tc. 99m Tc-YIGSR possesses many merits of imaging imaging: rapid visualization, high sensitivity and specificity, and satisfactory target / nontarget ratio. Our data suggest 99m Tc-YIGSR is a promising tumor radiotracer.