The testosterone deficiency syndrome (TDS) is characterised by numerous symptoms, including low libido, increased fat mass, fatigue, erectile dysfunction or osteoporosis, and up to 80% of men will experience some kind of ageing males' symptoms. This is caused by the age-depending decline in serum testosterone levels with concentrations being about 40–50% lower in men older than 60 years compared with young men. This significant decline in testosterone levels is further closely linked with medical conditions such as obesity, metabolic syndrome, diabetes or hypertension. The conventional way of treating TDS is the testosterone replacement therapy (TRT), for which preparations are on the market. Apart from the beneficial effects of TRT, significant adverse side effects have been described, and prostate cancer (PCa) as absolute contraindication is debated. Eurycoma longifolia (Tongkat Ali; TA) is natural alternative to TRT and has been shown to restore serum testosterone levels, thus significantly improving sexual health. This includes significant positive effects on bone health and physical condition of patients. In addition, a significant antihyperglycaemic effect and cytotoxicity against PCas cells has been shown. Thus far, at therapeutic concentrations, no significant side effects of the treatment were obvious. Therefore, TA might be a safe alternative to TRT.