Objective To measure DNA contents of spermatogenic cells and analyze the efficiency of spermatogenesis after testicular heating in rat Methods Eighty adult male Sprague-Dawley rats were randomly divided into experimental group (43°C, 30 min) and control group (22°C, 30 min). According to day 0.5, 1, 3, 6, 10, 25, 35 and 50 after local testicular heating, every group was divided into 8 subgroups:experimental subgroups (n=6) and control subgroups (n=4). DNA contents of various types of germ cells were observed with flow cytometry (FCM) in all groups. Results Compared with control groups, percentages of 4C cell (primary spermatocyte) in 0.5-35 d groups and percentages of 1C cell (spermatid and sperm) in 6-50 d groups significantly decreased in experimental groups (P<0.05), and percentages of 2C cell (spermatogonium and second spermatocyte) in 3 -35 d experimental groups increased significantly after heating (P<0.05). 4C:2C in all of 8 experimental groups and 1C:2C in 3-35 d experimental groups were down (P<0.05), and in 1 d experimental group 1C:4C was up after heating (P<0.05). Conclusions After being heated, the number of spermatocyte firstly decreased, and then that of spermatid and sperm decreased too. Heat influences several stages in spermatogenesis and results in suppression of spermatogenesis. Flow cytometry is an effective method for researching on the change of spermatogenesis and has significance on mechanism about changing of spermatogenic cells induced by heat. Objective To measure DNA contents of spermatogenic cells and analyze the efficiency of spermatogenesis after testicular heating in rat Methods Eighty adult male Sprague-Dawley rats were divided divided into experimental group (43 ° C, 30 min) and control group (22 ° C, 30 min) according to day 0.5, 1, 3, 6, 10, 25, 35 and 50 after local testicular heating, each group was divided into 8 subgroups: experimental subgroups (n = 6) and control subgroups (n = 4). DNA contents of various types of germ cells were observed with flow cytometry (FCM) in all groups. Results Compared with control groups, percentages of 4C cells (primary spermatocyte) in 0.5-35 d groups and percentages of 1C cells (spermatid and sperm) in 6-50 d groups significantly decreased in experimental groups (P <0.05), and percent percent of 2C cell (spermatogonium and second spermatocyte) in 3 -35 d experimental groups increased significantly after heating (P <0.05). 4C: 2C in all of 8 experimental groups and 1C: 2C in 3-35 d experimental groups were down (P <0.05), and in 1 d experimental group 1C: 4C was up after heating (P <0.05). Conclusions After being heated, the number of spermatocyte first decreased, and then that that spermatid and sperm decreased too. Heat influences several stages in spermatogenesis and results in suppression of spermatogenesis. Flow cytometry is an effective method for researching on the change of spermatogenesis and has significance on mechanism about changing of spermatogenic cells induced by heat.