The synthesis of steroidal derivatives containing [1,2,4]triazolo[1,5-a]pyrimidine derived from progesterone is described. The Claisen condensations of Δ1,4-pregnadien-3,20-dione and 4-chloro-Δ1,4-pregnadien-3,20-dione with dimethyl oxalate afforded 21-methoxalylpregn-1,4-diene-3,20-dione and 4-chloro-21-methoxalylpregn-1,4-diene-3,20-dione, respectively. Furthermore, the reactions of these compounds with 3-amino-1,2,4-triazole yielded the corresponding [1,2,4]triazolo[1,5-a]pyrimidine derivatives. The newly synthesised compounds were evaluated in vitro by means of sulforhodamine B assays for antiproliferative activity against HeLa and MCF-7 cells. [ABSTRACT FROM AUTHOR]