In this longitudinal case-control study, acute fracture was associated with low serum testosterone, which was transient in 43 % of men. While assessment of gonadal status is part of the assessment of bone fragility, measurement of testosterone in the early period after fracture may overestimate the prevalence of androgen deficiency. Measurement of circulating testosterone is recommended in the evaluation of bone fragility in men. Since acute illness can transiently decrease circulating testosterone, we quantified the association of acute fracture and serum testosterone levels. A case-control study was conducted involving 240 men with a radiologically confirmed minimal trauma fracture presenting to a tertiary referral hospital and 89 age-matched men without a history of minimal trauma fracture serving as controls. Follow-up testosterone levels 6 months after baseline were available for 98 cases and 27 controls. Results were expressed as the median and interquartile (IQR) range. Compared to controls, cases had lower total testosterone [TT, 7.2 (3.5, 10.8) vs 13.6 (10.9, 17.1) nmol/L, p < 0.001]. The 143 cases treated as inpatients had lower testosterone levels than the 97 cases treated as outpatients [TT 4.7 (2.3, 8.1) vs 10.3 (7.5, 12.7) nmol/L, p < 0.001]. Group differences in calculated free testosterone (cFT) were comparable to the group differences in TT. At follow-up, in 98 cases, median TT increased from 6.5 nmol/L (3.2, 8.5) to 9.6 nmol/L (6.9, 12.0) p < 0.0001, and SHBG remained unchanged. Of cases with low testosterone, 43 % with TT < 10 nmol/L and/or cFT < 230 pmol/L at presentation were reclassified as androgen sufficient at follow-up. TT was unchanged in the controls. Low testosterone levels in men presenting with an acute fracture may, at least in part, be due to an acute, fracture-associated, stress response. To avoid over diagnosis, evaluation for testosterone deficiency should be deferred until recovery from the acute event.