The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated the maximum concentration of dimethyl sulfoxide at the workplace (MAK value) of 50 ml/m3, considering the endpoints local and systemic toxicity as well as developmental toxicity. In a 13‐week inhalation study the olfactory and respiratory epithelia and the pharynx of rats were the target tissues, and reduction of body weight gain, possibly secondary to the irritation, was seen. The NOAEC for these effects is 964 mg/m3 (297 ml/m3, vapour). Since 2014 the Commission uses an empirical approach to set MAK values for substances with critical effects on the upper respiratory tract or the eyes. According to this approach, a MAK value of 50 ml/m3 can be calculated from this study, taking into account that a lower NOAEC has to be expected with chronic exposure. Therefore, the previous MAK value is retained. As local effects are critical, the assignment to Peak Limitation Category I and the excursion factor of 2 are retained. The borderline increase in incidences of pups with dilated renal pelvis seen in the developmental toxicity study was not confirmed in a screening study with rats according to OECD Test Guideline 421. However, in rabbits dimethyl sulfoxide causes kidney malformations with a NOAEL of 300 mg/kg bw. Therefore, damage to the embryo or foetus cannot be excluded even when the MAK value is observed and dimethyl sulfoxide is assigned to Pregnancy Risk Group B.