Ok, figured out to declare the struct in C# for the call into the Delphi DLL.   I did a sample program and sample entry points with smaller record structures to prove that it will work.  (can't use dynamic arrays, have to use "fixed" arrays).   However, another roadblock.    We have 3 paramters that are records in Delphi, and struct in C#.  It turns out that each of these records will be 62,000,     82,000,   and 27,000   bytes .    At run time, I get an exception that the second parameter is too large or complex.  (Internal limitation).   My guess is it can't marshall more than 64K.   Any ideas?