Pre-clinical toxicology studies in rodents and Phase I clinical trial data are summarised for 14 novel anticancer therapies. With only one exception, an antifolate antimetabolite, rodent toxicology predicted a safe Phase I trial starting dose and the majority of the dose limiting toxicities, in particular haematological toxicity. For targeted agents with well-defined pharmacodynamic markers, illustrated in the current study by 3 anti-endocrine drugs and one resistance modifier, the definition of a maximum tolerated dose can be avoided. Together with earlier data, the current study confirms that pre-clinical toxicology studies in a non-rodent species are not routinely needed for the safe conduct of early clinical trials with new cancer chemotherapies.