Media commentators have explained away recent sex scandals in schools of modern yoga as inevitable because of physical yoga’s origins in tantric sex cults. Scholarship on yoga has, in the main, supported this view. Yet philological analysis of the texts of Haṭhayoga shows its techniques to be a blend of visualisation-based non-physical tantric yoga with the physical techniques of an older ascetic tradition in which celibacy was paramount. This paper seeks to examine attitudes towards sex in haṭhayogic texts by focussing on vajroli mudrā, the technique of urethral suction, the aim of which is commonly understood to be the absorption of commingled sexual fluids. Analyses of its descriptions in the early haṭhayogic corpus show, however, that this is anomalous; in the majority of texts the purpose of the vajroli mudrā is sexual continence. Furthermore, ethnographic and medical investigation suggests that it is physiologically impossible to absorb the products of sexual intercourse through the penis while copulating: a catheter is required. The texts of Haṭhayoga brought the previously secret techniques of celibate ascetics to a householder audience and had to adjust their aims accordingly. In conclusion, this paper will summarise this process and the texts’ explicit pronouncements on sex.