Minor tick marks are called minor because they should be subordinate to major tick marks. And it is so in both IDL Direct Graphics and IDL Object Graphics that they are drawn to a proportion of major tick marks. And anyway, if your minor tick marks are to have a length of 1.0, what was your plan for the major tick marks? In any case, I do not want to discourage you completely. One option - I say this theoretically because I am not trying it as I enter this tip - is to superimpose an extra AXIS on the top of an axis that is provided by PLOT. Both axes would have suppressed MINOR tick marks, but they could have differing MAJOR tick mark location and length specifications. The MAJOR ticks of the PLOT, for example, might be the 1.0 long minor ticks that you want. The MAJOR ticks of the AXIS could be the major ticks you want in your plot visualization. The above explains the Direct Graphics algorithm, but a similar algorithm could be implemented in IDL Object Graphics as well. James Jones